Jasmina B. Nikolić

Detailed solvent, structural, quantum chemical study and antimicrobial activity of isatin Schiff base

The ratios of E/Z isomers of sixteen synthesized 1,3-dihydro-3-(substituted phenylimino)-2H-indol-2-one were studied using experimental and theoretical methodology. Linear solvation energy relationships (LSER) rationalized solvent influence of the solvent-solute interactions on the UV-Vis absorption maxima shifts (νmax) of both geometrical isomers using the Kamlet-Taft equation. Linear free energy relationships (LFER) in the form of single substituent parameter equation (SSP) was used to analyze substituent effect on pKa, NMR chemical shifts and νmax values. Electron charge density was obtained by the use of Quantum Theory of Atoms in Molecules, i.e. Baders analysis. The substituent and solvent effect on intramolecular charge transfer (ICT) were interpreted with the aid of time-dependent density functional (TD-DFT) method. Additionally, the results of TD-DFT calculations quantified the efficiency of ICT from the calculated charge-transfer distance (DCT) and amount of transferred charge (QCT). The antimicrobial activity was evaluated using broth microdilution method. 3D QSAR modeling was used to demonstrate the influence of substituents effect as well as molecule geometry on antimicrobial activity.

A study of the barrier properties of polyethylene coated with nanocellulose/magnetite composite film

The morphological, thermal and barrier properties of low-density polyethylene/polycaprolactone-modified nanocellulose hybrid materials were investigated in this study. Nanocellulose/magnetite (NC-Fe3O4) nanocompo- site and maleic acid functionalized NC/magnetite (NCMA-Fe3O4) nanocom- posite were prepared and used as fillers at various concentrations (5, 10 and 15 wt. %) in the polycaprolactone (PCL) layer. PE was coated with a PCL/NC/ /magnetite layer. The addition of the filler did not unfavorably affect the inherent properties of the polymer, especially its barrier properties. Oxygen permeation measurements showed that the oxygen barrier properties of mag- netite enriched PCL film were improved due to the chemical activity of the added material. The highest level of the barrier capacity was observed for PE samples coated with a PCL-based composite with NCMA-Fe3O4 micro/nano- filler, which implies a significant contribution of the surface modification of the nanocellulose with maleic anhydride residue to the improved barrier pro- perties.